What about the attacker who compromises your home computer and then is using it remotely while you are not home?
An IP based check won't help you there. This canary would.
An IP based check won't help you there. This canary would.
Suppose he uses http://googleblog.blogspot.com/2011/02/advanced-sign-in-secu... and has it remember the second authentication for 30 days (available from a checkbox). Then someone who has compromised his machine and has installed a keylogger can find it password, and log back in as him from that machine when he is not there. Two-factor has not saved you. Nor has the IP check.
And yes, you're right. If someone owns your personal machine you have a whole lot of other problems. This fact makes discovering that someone owns your machine more important, not less.